docs: def decrypt_file(file, key):
      """
      Decrypts the file ``file``.
  
      The encrypted file is assumed to end with the ``.enc`` extension. The
      decrypted file is saved to the same location without the ``.enc``
      extension.
  
      The permissions on the decrypted file are automatically set to 0o600.
  
      See also :func:`doctr.local.encrypt_file`.
  
      """
      if not file.endswith('.enc'):
          raise ValueError("%s does not end with .enc" % file)
  
      fer = Fernet(key)
  
      with open(file, 'rb') as f:
          decrypted_file = fer.decrypt(f.read())
  
      with open(file[:-4], 'wb') as f:
          f.write(decrypted_file)
  
      os.chmod(file[:-4], 0o600)